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	$118.69	7.586%	$127.6938	$127.69	$127.70	$127.70
Purchase #2	$33.53	12.673%	$37.7793	$37.78	$37.80	$37.80
Purchase #3	$101.55	8.555%	$110.2376	$110.24	$110.25	$110.20
Purchase #4	$218.36	8.260%	$236.3965	$236.40	$236.40	$236.40
Purchase #5	$139.67	11.538%	$155.7851	$155.79	$155.80	$155.80
Purchase #6	$53.40	10.833%	$59.1848	$59.18	$59.20	$59.20
Purchase #7	$174.78	7.146%	$187.2698	$187.27	$187.25	$187.30
7 purchase totals =	$839.98		$914.3469	$914.35	$914.40	$914.40