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	$180.91	10.786%	$200.423	$200.42	$200.40	$200.40
Purchase #2	$182.92	12.126%	$205.1009	$205.10	$205.10	$205.10
Purchase #3	$52.57	12.713%	$59.2532	$59.25	$59.25	$59.30
Purchase #4	$232.57	12.401%	$261.411	$261.41	$261.40	$261.40
Purchase #5	$22.79	11.868%	$25.4947	$25.49	$25.50	$25.50
Purchase #6	$158.46	8.344%	$171.6819	$171.68	$171.70	$171.70
Purchase #7	$152.25	12.515%	$171.3041	$171.30	$171.30	$171.30
7 purchase totals =	$982.47		$1,094.6688	$1,094.65	$1,094.65	$1,094.70