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	$144.32	5.422%	$152.145	$152.15	$152.15	$152.10
Purchase #2	$80.43	5.784%	$85.0821	$85.08	$85.10	$85.10
Purchase #3	$70.41	5.512%	$74.291	$74.29	$74.30	$74.30
Purchase #4	$90.86	8.820%	$98.8739	$98.87	$98.85	$98.90
Purchase #5	$98.74	13.322%	$111.8941	$111.89	$111.90	$111.90
Purchase #6	$228.47	13.623%	$259.5945	$259.59	$259.60	$259.60
Purchase #7	$201.28	10.653%	$222.7224	$222.72	$222.70	$222.70
7 purchase totals =	$914.51		$1,004.6030	$1,004.59	$1,004.60	$1,004.60