Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$100.67	10.204%	$110.9424	$110.94	$110.95	$110.90
Purchase #2	$146.70	12.649%	$165.2561	$165.26	$165.25	$165.30
Purchase #3	$133.64	12.515%	$150.365	$150.37	$150.35	$150.40
Purchase #4	$250.89	13.600%	$285.011	$285.01	$285.00	$285.00
Purchase #5	$37.40	10.276%	$41.2432	$41.24	$41.25	$41.20
Purchase #6	$232.52	10.425%	$256.7602	$256.76	$256.75	$256.80
Purchase #7	$153.59	3.368%	$158.7629	$158.76	$158.75	$158.80
7 purchase totals =	$1,055.41		$1,168.3408	$1,168.34	$1,168.30	$1,168.40