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	$88.33	10.608%	$97.7	$97.70	$97.70	$97.70
Purchase #2	$67.43	7.154%	$72.2539	$72.25	$72.25	$72.30
Purchase #3	$62.96	6.465%	$67.0304	$67.03	$67.05	$67.00
Purchase #4	$153.95	6.629%	$164.1553	$164.16	$164.15	$164.20
Purchase #5	$228.77	11.264%	$254.5387	$254.54	$254.55	$254.50
Purchase #6	$159.33	9.529%	$174.5126	$174.51	$174.50	$174.50
Purchase #7	$225.65	3.281%	$233.0536	$233.05	$233.05	$233.10
7 purchase totals =	$986.42		$1,063.2445	$1,063.24	$1,063.25	$1,063.30