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	$92.70	7.379%	$99.5403	$99.54	$99.55	$99.50
Purchase #2	$98.33	11.137%	$109.281	$109.28	$109.30	$109.30
Purchase #3	$128.38	13.788%	$146.081	$146.08	$146.10	$146.10
Purchase #4	$151.79	6.242%	$161.2647	$161.26	$161.25	$161.30
Purchase #5	$93.36	10.262%	$102.9406	$102.94	$102.95	$102.90
Purchase #6	$165.57	5.474%	$174.6333	$174.63	$174.65	$174.60
Purchase #7	$216.63	6.853%	$231.4757	$231.48	$231.50	$231.50
7 purchase totals =	$946.76		$1,025.2166	$1,025.21	$1,025.30	$1,025.20