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	$176.80	10.452%	$195.2791	$195.28	$195.30	$195.30
Purchase #2	$88.61	8.734%	$96.3492	$96.35	$96.35	$96.30
Purchase #3	$148.30	11.469%	$165.3085	$165.31	$165.30	$165.30
Purchase #4	$120.84	5.637%	$127.6518	$127.65	$127.65	$127.70
Purchase #5	$62.84	10.631%	$69.5205	$69.52	$69.50	$69.50
Purchase #6	$196.43	13.251%	$222.4589	$222.46	$222.45	$222.50
Purchase #7	$41.46	10.193%	$45.686	$45.69	$45.70	$45.70
7 purchase totals =	$835.28		$922.2540	$922.26	$922.25	$922.30