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	$192.58	13.208%	$218.016	$218.02	$218.00	$218.00
Purchase #2	$32.50	11.653%	$36.2872	$36.29	$36.30	$36.30
Purchase #3	$183.48	4.460%	$191.6632	$191.66	$191.65	$191.70
Purchase #4	$187.32	11.264%	$208.4197	$208.42	$208.40	$208.40
Purchase #5	$134.54	8.827%	$146.4158	$146.42	$146.40	$146.40
Purchase #6	$53.62	6.809%	$57.271	$57.27	$57.25	$57.30
Purchase #7	$164.25	4.869%	$172.2473	$172.25	$172.25	$172.20
7 purchase totals =	$948.29		$1,030.3202	$1,030.33	$1,030.25	$1,030.30