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	$154.64	5.108%	$162.539	$162.54	$162.55	$162.50
Purchase #2	$73.51	12.491%	$82.6921	$82.69	$82.70	$82.70
Purchase #3	$156.89	7.872%	$169.2404	$169.24	$169.25	$169.20
Purchase #4	$91.55	9.645%	$100.38	$100.38	$100.40	$100.40
Purchase #5	$175.91	9.441%	$192.5177	$192.52	$192.50	$192.50
Purchase #6	$238.55	6.602%	$254.2991	$254.30	$254.30	$254.30
Purchase #7	$153.58	12.542%	$172.842	$172.84	$172.85	$172.80
7 purchase totals =	$1,044.63		$1,134.5103	$1,134.51	$1,134.55	$1,134.40