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	$89.64	10.328%	$98.898	$98.90	$98.90	$98.90
Purchase #2	$50.30	4.153%	$52.389	$52.39	$52.40	$52.40
Purchase #3	$241.55	4.496%	$252.4101	$252.41	$252.40	$252.40
Purchase #4	$210.90	4.272%	$219.9096	$219.91	$219.90	$219.90
Purchase #5	$241.73	13.220%	$273.6867	$273.69	$273.70	$273.70
Purchase #6	$180.32	5.503%	$190.243	$190.24	$190.25	$190.20
Purchase #7	$75.82	7.614%	$81.5929	$81.59	$81.60	$81.60
7 purchase totals =	$1,090.26		$1,169.1293	$1,169.13	$1,169.15	$1,169.10