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	$190.60	10.860%	$211.2992	$211.30	$211.30	$211.30
Purchase #2	$9.25	10.850%	$10.2536	$10.25	$10.25	$10.30
Purchase #3	$163.81	4.459%	$171.1143	$171.11	$171.10	$171.10
Purchase #4	$141.89	12.682%	$159.8845	$159.88	$159.90	$159.90
Purchase #5	$180.82	10.527%	$199.8549	$199.85	$199.85	$199.90
Purchase #6	$249.50	3.709%	$258.754	$258.75	$258.75	$258.80
Purchase #7	$89.39	8.379%	$96.88	$96.88	$96.90	$96.90
7 purchase totals =	$1,025.26		$1,108.0405	$1,108.02	$1,108.05	$1,108.20