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	$179.27	12.645%	$201.9387	$201.94	$201.95	$201.90
Purchase #2	$54.28	6.750%	$57.9439	$57.94	$57.95	$57.90
Purchase #3	$138.89	12.484%	$156.229	$156.23	$156.25	$156.20
Purchase #4	$79.37	12.352%	$89.1738	$89.17	$89.15	$89.20
Purchase #5	$217.48	11.644%	$242.8034	$242.80	$242.80	$242.80
Purchase #6	$197.54	13.303%	$223.8187	$223.82	$223.80	$223.80
Purchase #7	$54.33	11.574%	$60.6182	$60.62	$60.60	$60.60
7 purchase totals =	$921.16		$1,032.5257	$1,032.52	$1,032.50	$1,032.40