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	$73.49	5.394%	$77.4541	$77.45	$77.45	$77.50
Purchase #2	$19.77	10.748%	$21.8949	$21.89	$21.90	$21.90
Purchase #3	$6.68	11.322%	$7.4363	$7.44	$7.45	$7.40
Purchase #4	$31.35	7.281%	$33.6326	$33.63	$33.65	$33.60
Purchase #5	$26.69	8.378%	$28.9261	$28.93	$28.95	$28.90
Purchase #6	$163.68	12.600%	$184.3037	$184.30	$184.30	$184.30
Purchase #7	$86.45	3.695%	$89.6443	$89.64	$89.65	$89.60
7 purchase totals =	$408.11		$443.2920	$443.28	$443.35	$443.20