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	$53.88	11.165%	$59.8957	$59.90	$59.90	$59.90
Purchase #2	$69.34	4.649%	$72.5636	$72.56	$72.55	$72.60
Purchase #3	$168.73	11.468%	$188.08	$188.08	$188.10	$188.10
Purchase #4	$93.76	5.375%	$98.7996	$98.80	$98.80	$98.80
Purchase #5	$229.43	5.450%	$241.9339	$241.93	$241.95	$241.90
Purchase #6	$161.38	3.541%	$167.0945	$167.09	$167.10	$167.10
Purchase #7	$210.34	3.275%	$217.2286	$217.23	$217.25	$217.20
7 purchase totals =	$986.86		$1,045.5959	$1,045.59	$1,045.65	$1,045.60