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	$167.71	4.611%	$175.4431	$175.44	$175.45	$175.40
Purchase #2	$41.68	8.804%	$45.3495	$45.35	$45.35	$45.30
Purchase #3	$243.39	13.171%	$275.4469	$275.45	$275.45	$275.40
Purchase #4	$235.32	13.555%	$267.2176	$267.22	$267.20	$267.20
Purchase #5	$96.60	4.321%	$100.7741	$100.77	$100.75	$100.80
Purchase #6	$83.33	11.480%	$92.8963	$92.90	$92.90	$92.90
Purchase #7	$246.30	9.430%	$269.5261	$269.53	$269.55	$269.50
7 purchase totals =	$1,114.33		$1,226.6536	$1,226.66	$1,226.65	$1,226.50